[chipmunk]

Have Coleman Evcon heating A/C system. Thermostat has setting for fan auto or manual fan but I don't know how it turns on although when temp in the house gets 90 degrees plus the fan goes on automatically. Spooky!!

How can I get fan to work if temp outside is 80 degrees or lower?

Appreciate help. Thanks

[hkstroud]

What temperature do you have the A/C set to come on? Is this a digital or analog thermostat?

[chipmunk]

Hi,

Thanks for answering. Sorry for the delay but was caring for newborn beasties and a few were having physical problems.

My thermostat is set at 84. Comfortable enough since I live in Utah where it is a dry climate. The thermo is analog.

Still can't understand why it automatically turns on when the house heats up over 90.

I'd really appreciate your opinion about this mystery and how I can get the fan on when at night, the temp gets cool. Originally, from NY so my windows are closed at night.

Thanks again Chipmunk

[Kender]

There is a temperature switch that turns the fan ON automatically at 90. When you turn on the heat the thermostat only turns on the heating elements. When the inside of the system gets up to 90 then that switch will turn on the fan.

It is a round disk that normally has 2 wires going into it. It should be labeled F90-10
The "F" is for fan, The 90 is temperature, The "-10" is the swing. With -10 it turns on at 90 and off at 80.

You can buy those at any temp range, just make sure you don't go above 90 or it might overheat in the heating cycle because it will keep the fan off longer.

[hkstroud]

You have one of those old (good) round thermostats right? You set it by turning th dial, the room temperature is shown below. You have it set to come on at 84 but it doesn't come on until the actual temperature in the house gets to 90. Is that all correct?

[chipmunk]

HI,

Yep, It's one of those old, round thermos.

Honestly speaking, this is the first time I've ever lived in a place with a thermo. In NY, the boiler goes on and heats the water for all 5 floors of the 100 year old apt. building. In summer, we relied on the window A/C. Don't laugh!!

Now that I'm in a real house, this stuff is Martian. But, it's fun to learn. Heck, I changed electrical swithches (gas plugs still in the ceiling) and copper plumbing because there ain't no such thing as plastic piping in those old buildings. Watched my dad do this when we came to the US and dad was a super. I was 6 but it was all so fascinating and I learned and soaked it up. Now I have to soak up new info and I am ready. Thank you folks for all your help.

OK, the A/C doesn't go on until I turn on the main switch for "cool". I watch the temp in the house and once it gets to 90, I go to the main furnace and turn on the cool. When the temp goes to 82-84, I turn off the main switch. It doesn't go on, automatically if the house goes over 84.

The fan switch on the thermo doesn't seem to work, at all. I tried turning it to auto, I tried turning it to heat, I tried everything. But somehow, the fan is on when I come home and the temp in the house is over 90.

My cats have their belliies against the walls. Sign that it is super hot.

Now, if I can only get the fan to go on when the night temp is in the 70s, it would be a blessing.

Is this OK for an explanation? I'm so confused and dehydrated!

Thanks folks

[hkstroud]

Not only are you confused, by now you furnace and A/C are confused. Why you doing all that work. Its supposed to be automatic. You are doing the work of the thermostat.

I assume you have a hot air furnace and central A/C unit. You thermostat should have a cool, off and heat switch or setting. Your fan switch on the thermostat should have an on and an auto.
If your furnace and A/C are not tied together as one unit, your thermostat will only have a off and a cool setting.

I'm not sure what switch you are talking about when you say main switch on the furnace. If it is the electrical supply switch (looks just like a regular light switch), turn it on and leave it alone.

Set you thermostat to cool, set you fan switch to auto. Turn the dial on your thermostat to the temperature you want the house to be.

Let me know what happens. If necessary we will calibrate your thermostat.

[chipmunk]

Hi Harold,

OK, the main switch I am referring to is on the tall 6 foot unit, itself. The switch is almost 130 degrees, anglewise. Pushed down, it says "cool", pushed center, it says "off" and pushed up, it says "heat".

The thermo is Honeywell and is exactly as you described.

Presently, I have the main switch on the middle "off" position. Neither cool nor heat.

The thermo is set on cool / fan auto.

The temp is now set for 72 and reads 86 in the house, right now.

The 6 foot unit sounds as if there's juice comig in, electrically but there is no air flowing from the vents.

I'll wait. Thanks for your guidance. At least I don't feel too frustrated. And super thanks for your patience. Nonna aka Chipmunk

[hkstroud]

Hi Nonna,

Turn that main switch on the furnace to cool and leave it there until winter time. Set thermostat to 80 and leave it alone. I want to see how much difference there is between that setting and the actual temperature inside the house.

[chipmunk]

Hi Harold,

OK, "cool" on main equipment, 80 for thermo and let you know what the temp inside will be.I'll let you know what the temp inside is at 0500hrs and when I come home from work at 1300hrs. The temp on thermo doesn't show anything beyond 90.

The thermo seems to be CT87 Honeywell, as far as the website for Honeywell is. Now, please don't laugh but if all appears working, should there be a small spark coming from the thermo when it's working? I sure hope you don't say yes because I played with that area when I first moved in to stop the spark. Also, when I removed the plate there's a small bulb with mercury in it but the very tip of the bulb seems darkened. Is this normal? It's the thermometer, right?

Sorry for the kindergarten description but that's how I can learn, it soaks in better.

Thanks a million for your patience. Nonna aka Chipmunk

[hkstroud]

Yes, there is often a spark when the thermostat turn off, quite normal. That darkened area is just where the manufactor sealed the end of the glass bulb after putting the murcury in. This is the thermostat half of the device. The coil spring that that bulb is attached to expands and contracts with changes in temperature. That causes the bulb to rock back and forth. When the bulb rocks to one side, the mecury flows to that end closes the electrical circuit between the two wires.

[chipmunk]

Hi Harold,

I did as you recommended and set the thermostat to 80. When temp outside was 76, the A/C didn't turn on. When temp was 90 outside the A/C didn't turn on.

Would it be costly to replace the thermo and if I do should I get the same type?

Thanks Nonna